The invention relates generally to fuel nozzles for combustors and, specifically, to the introduction of fuel and air from a fuel nozzle into a combustion zone of the combustor for a gas turbine.
Gas turbines that have combustors operating at low oxygen conditions are generally referred to as low oxygen gas turbines. These gas turbines may be used in carbon capture arrangements and in arrangements having high exhaust gas recirculation.
The working fluid in a gas turbine is generally the gas that is pressurized in the compressor, heated in the combustor and driving the turbine. The working fluid in a low oxygen gas turbine typically has a reduced concentration of oxygen as compared to the oxygen concentration in normal atmospheric air. For example, the working fluid may be a combination of exhaust gas from the gas turbine and atmospheric air. Due to the presence of exhaust gases, the working fluid has a relatively low oxygen content as compared to atmospheric air.
Oxygen is needed for combustion in the combustor. A working fluid having a reduced oxygen concentration requires a combustor configured to provide complete and stable combustion in reduced oxygen conditions. To provide sufficient oxygen for combustion, an oxidizer gas may be injected with the fuel into the combustor. The oxidizer gas may be atmospheric air, pure oxygen, a mixture of oxygen and carbon dioxide (CO2) or another oxygen rich gas.